Can submaximal exercise variables predict peak exercise performance in women with chronic fatigue syndrome?

This study aimed at examining whether physiological exercise variables at the submaximal level, defined as 75% of the age-predicted target heart rate, are able to predict peak exercise performance in women with chronic fatigue syndrome (CFS) (n=222). Subjects performed a bicycle ergometric test against a graded increase in workload until exhaustion with continuous monitoring of electrocardiographic and ventilatory variables. Oxygen uptake at the submaximal level (VO2SUBMAX) correlated strongly with peak oxygen uptake (VO2PEAK) (r=0.70). For the prediction of VO2PEAK, linear regression analysis determined the line of best fit as: VO2PEAK=0.95xVO2SUBMAX+372.3. Using this equation, the mean error in the prediction was 14.6+/-11.2% (range 0.1-63.7%). It is concluded that the prediction of VO2PEAK based on VO2SUBMAX might be useful for analyzing group differences or treatment effects but not for individual (clinical) purposes.